Portable computing devices such as laptops, media players, cellular phones, head mounted displays (HMDs) etc., have become small, light and powerful. One factor contributing to this reduction in size can be attributed to the manufacturer's ability to fabricate various components of these devices in smaller and smaller sizes while in most cases increasing the power and or operating speed of such components. Another factor contributing to the reduction in size is that from a visual standpoint, users often find compact and sleek designs of consumer electronic devices more aesthetically appealing and thus, demand compact and sleek designs. The trend of smaller, lighter, more compact and powerful presents continuing challenges in the design of portable computing devices and its associated components.
Printed circuit boards (PCBs) are used in most portable computing devices. In general, a PCB accommodates the interconnection of various electrical components. For example, a plurality of transistors, capacitors, inductors, and the like, may be interconnected using a PCB. The PCB may have a plurality of vias and traces to accommodate interconnecting the various electrical components mounted to the PCB. Furthermore, the PCB may include different conductive and nonconductive dielectric layers. The conductive layers may incorporate the plurality of vias and traces, while the nonconductive or insulating dielectric layers may function to separate or isolate one or more of the conductive layers. A PCB that includes a plurality of conductive and nonconductive layers is often referred to as a multilayer PCB.
A computing device incorporating one or more PCBs may apply a voltage to the electrical components associated with the one or more PCBs. The voltage applied to the electrical components may cause the one or more of the electrical components to change shape or deform due to electrostriction. For example, a voltage may cause some of the electrical components to vibrate or pulsate. The vibration caused by the electrical components may be transmitted to the PCB and cause the PCB to vibrate. The vibration of the PCB may be undesirably audible to a user of the computing device. Human perceptible sound associated with the vibration of a PCB is particularly problematic when associated with computing devices (e.g., cell phones and HMDs) that are often used close to a user's ear.